The invention relates to a self-leveling device, preferably an optical display device such as a multiple-axis laser, a leveling device or a rotational laser having a suspension for a free-hanging pendulum.
In tiltable devices of this type the pendulum systems, to which this invention is limited, at least one freely hanging, gravity-acting pendulum is used as the measurement system carrier and is guided by gravity.
U.S. Pat. No. 5,459,932 discloses an optical display device characterized by a laser diode that produces a visible laser beam which, together with an optical beam splitter, is mounted on a freely hanging, eddy-current damped pendulum connected by means of a coil spring using a flexible-elastic suspension. The power supply to the laser diode is achieved via at least one freely suspended fine wire. In the event of vibration or shock the coil spring itself executes complex lateral and rotational oscillations around its position of rest because of which additional damping is required in proximity to the suspension.
U.S. Pat. No. 5,917,587 discloses an optical display device in which the prism is fixed using a flexible-elastic and dampening suspension in the form of a rubber strip.
DE19810447A1 discloses as the resilient suspension a flexible foil hinge or a flexible-elastic strip formed of a rubber-like elastic material. The suspension is comprised of a multi-component frame structure with connector pins for conductive contact with the housing or with the measurement system carrier of the pendulum, whereby a prefabricated foil hinge or band is arranged between the individual carrier plates of the frame structure, the foil hinge or band having a strip-like segment and is fastened bilaterally to adjacent mounting segments. The film hinge or strip incorporates circuits or wires for power supply to a laser diode arranged on the pendulum acting as the measurement system carrier. The suspension forms an integral unit which as such can be easily installed or replaced in the housing. Its disadvantage is that it requires two foil hinges or bands to be arranged perpendicular to each other and axially behind each other in the manner of a cardan or universal joint in order to allow free lateral gravity-acting alignment on all sides.
U.S. Pat. No. 5,541,727 discloses the elastic and dampening suspension in an optical projection tool with limited precision as a compact, dumbbell shaped highly elastic component made of rubber that extends radially and projects bilaterally axially through apertures.
The object of the invention is to achieve a reduction in the dimensions of the arrangement forming the suspension and further, a reduction in the components required for the suspension.
Essentially, a modular unitary suspension for a measurement system carrier of a tiltable housing, the carrier being designed as a gravity-acting pendulum freely oscillating in at least one lateral direction, is characterized by a flexible connection means comprised of a rubber-like elastic material formed as a compact component and having at least in one axial region of flexure a rotationally-symmetrical flexural resistance moment.
Thereby the identical flexural resistance and a comparable torsion resistance is created by the connector assembly via the axial region of flexure in all directions perpendicular to the axis. As a result the components required for the creation of a cardan-like element are eliminated and the arrangement becomes axially reduced in size. The viscoelasticity of the rubber-like elastic material provides a more effective self-dampening effect for the oscillation modes of the connector assembly, whereby no additional dampening of the connector assembly is required.
The connector assembly is advantageously designed to be rotationally symmetrical, dumb-bell shaped, whereby a thin section forms the flexural region and the bilateral cross-sectional thickened sections serve to fasten the connector assembly to their respective mounting assemblies.
The bilateral and axially extending cross-sectional thickened sections each advantageously have radial recesses for interlocking engagement into axial through-holes of the respective mounting assemblies.
The outside axial regions of the cross-sectional thickenings taper inwardly at the ends, whereby they can be forced through the through holes by light axial pressure and there automatically engage into radially projecting catches.
The suspension includes electrical connections extending over the flexible fastening assembly, the electrical connections connecting the measurement system into an electrical circuit in the rest of the housing via at least two conductive current paths.
A further advantage is the fact that the electrical connections are connected to contact surfaces on the mounting assemblies established bilaterally with the connector assembly and over which electrical contact can be made from the housing to the pendulors measurement system carrier.
The electrical connections are advantageously formed as flexible fine wires or stranded wires that suspendedly bridge the connector assembly and further advantageously wrap around its axial mid region in proximity to the oscillation midpoint at least over a half-space.
Alternatively, the electrical connections are lead through the connector assembly that is coaxially hollow at least in the region of flexure and then further are advantageously strain-resistantly connected to the structures for the absorption of axial traction forces.
Further alternatively, at least one electrical connection is arranged coaxially helically around the resilient connector assembly.
Moreover alternatively, several additional electrical connections are advantageously arranged circumferentially equally spaced, radially around the flexible connector assembly, the electrical connections being designed to be helical in shape.
The electrical connections can be further alternatively designed as printed circuits on the surface of the axial midsection of the connector assembly which furthermore advantageously surround the structures helically and further advantageously affords transition to recessed contacts inside of the recesses, the contacts being electrically connectable with the respective contact surfaces of the respective mounting assemblies.
The connector assembly is comprised advantageously of a conductive rubber-like elastic material such as, for example, polyanliline, polypyrol, or an elastomer filled with graphite and/or a conductive carbon, whereby at least one current path of the circuit is designed through the connector assembly itself.